Resistor



' sept. 2o, 1932. w F. STEENWEG 1,878,014

RESISTOR Filed Dec. ll. 1930 wllnlulii j muy M l! L; E

f Patented Sept. 20, 1932 WILLIAM F. STEENW EG, F MILWAUKEE,

WISCONSIN, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO ALLEN-BRADLEY COMPANY,0F MILWAUKEE, WISCONSIN, A. CORPORA- TION 0F WISCONSIN RESISTORApplication led December This invention relates to certain new anduseful improvements in resistors particularly adapted for use in theignition circuit of an automotive vehicle equipped with a radio receiverfor the purpose of eliminating the electrical interference ofdisturbance produced by the discharge of current across the spark plugsduring operation of the vehicle.

It is an object of this invention to provide a resistor of the generalcharacter described in my copending application Serial No. 390,- 836,filed Sept. 6, 1929, and having means thoroughly shielding andprotecting the element against moisture.

Another object of this invention resides in the provision of a resistorof the character described wherein the resistor' elementy per se, isthoroughly shielded but, at the same time, free expansion andcontraction of the device under temperature changes is freelyaccommodated without in any wise disturbing the electrical connectionstherewith.

A more specific object of this invention resides in the provision of anelectrical resistor unit of the character described having a moistureproof` housing of non-conductive material, terminals carried by thehousing at opposite ends and electrically connected with the unit andyieldable means within the housing and disposed between the resistorunit and an adjacent terminal to accommodate expansion and contractionof the unit without disturbing the electrical connection of the unitwith the terminal.

With the above and other objects in View which will appear as thedescription proceeds, my invention resides in the novel construction,combination and arrangements of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of lthehercindisclosed invention may be made as come within the scope of theclaims.

In the accompanying drawing, I have il- 11, 1930. Serial No. 501,703.

lustrated two complete examples of the physical embodiment of myinvention constructed according to the best modes I have so far devisedfor the practical application of the principles thereof, and in whichFigure 1 is a view, partly in side elevation and partly inlongitudinalsection, illustrating my improved resistance unit as appliedto a spark plug, only the upper terminal portion of the plug beingillustrated;

Figure 2 is a view, partly in elevation and partly in section, of amodified form of resistance unit inserted in the high tension line tothe distributor;

Figure 3 is a transverseL sectional view taken through Figure 2 on theplane of the line 3-3; and

Figure 4 is a diagrammatic view illustrat- `ing a conventional ignitioncircuit of an automotive vehicle esuipped with my improved resistor.

Referring now more particularly to the accompanying drawing, in whichlike numerals designate like parts throughout the Several views, 5represents' a spark plug of con- 7. ventional construction having a bodymem- Y ber 6 of insulation in which the central electrode, not shown, ofthe plug is axially embedded the electrode having a threaded stud orother terminal means 7 at its upper end for receiving one end of aterminal 8 of the improved resistor unit indicated generally as 9.

The resistor unit comprises a resistance element 10 molded of acomposition of ingredients including a filler, a binder and a conductorin proportions to provide the desired conductive characteristics. Theelement 10 is of the type covered by Letters Patent Number 1,816,194, i.e., the resistance value of its end portions is materially lower thanthat of its medial portions. The resistance element is secured Withinthe bore 11 of a preferably moisture proof protecting housing 12 havingone end closed by a metal cap 13 clinched over a bead or ange 14, as at15, the cap having n A closed by a terminal stud 20 having an inner head21, a hex head 22 spaced therefrom and an outer threaded end 23, thestud 20 being secured in position by molding the housing 12 thereabout.The threaded end 23 of the stud is adapted to receive a head member 24for receiving an electrical conductor 32.

The resistor element proper is inserted in the housing 12 from its endclosed by the cap 13 prior to the attachment of the cap thereto and ayieldable conductor 25, illustrated in the present instance as being aspring member, is inserted in the bore 11 after the resistance element.Attachment of the cap 13 over the end of the housing places member 25under compression so that a positive electrical connection between thelow resistance ends of the resistance element and the adjacent terminalmembers is maintained at all times and expansion and contraction of theparts compensated for. The yielding tension afforded by the member 25also accommodates any variations in the dimensions of elements.

In Figure 4, is illustrated a conventional ignition circuit in which thebattery 26, upon closing of an ignition switch 27 is connected with acircuit breaker 28, the stationary contact of which is connected withthe primary of an induction coil 29. The secondary of the induction coil29, as customary, is connected with the distributor arm 30 whichcooperates with the ter'minals 31 to select the spark plug to be fired.From the terminals 31 the conductor32 leads to terminals, not shown,electrically connected with the members 24 which in turn are connectedwith the i electrodes of the spark plug through the resistance element.A resistance element 33 is interposed between the secondary of theinduction coil and ground 34, the value of which is preferably the sameas that of the units 9 at the different spark plugs, which has beenfound to be approximately 25,000 ohms, although this value may change asconditions warrant.

The unit 33 is identical with the unit 9 with the exception that in lieuof the terminal 8 at one end a socket type terminal 35 is substitutedand in lieu of the type of terminal disclosed at the opposite end of theunit 9 a spring type socket terminal 36 is provided to facilitate itsconnection with the conventional distributor.

From the foregoing description, taken in connection with theaccompanying drawing,

it will be readily apparent to those skilled in the art to which aninvention of the character described appertains, that an efficient andpractical method of eliminating undesirable oscillations usuallyncontended with in an ignition circuit and which, if unprevented,produce excessive interference with radio reception by a receiverlocated within the receptacle, is provided and further that a highlyeiiicient .and practical construction of resistance unit for thispurpose is provided.

What I claim as my invention is:

l. A device for eliminating radio interference arising from highfrequency oscillations produced by the discharge of a spark plug,comprising a tubular housing of insulating material, a terminal contactat each end portion of the housing, a self-supporting electricalresistance element having its integral end portions of lower resistancevalue than its medial portion, said element being disposed within thetubular housing to electrically bridge the terminal contacts, andexpansible means within the housing for maintaining a tension betweenthe low resistance end partions of the element and the adjacent terminalcontacts to insure a good electrical conp nection between the elementand the terminal contacts.

2. A device for eliminating radio interference arising from highfrequency oscillations produced by the discharge of a spark plug,comprising a tubular housing of insulating material, a terminal contactat each end portion of the housing, a self-supporting electricalresistance element having its integral end portions of lower resistancevalue than its medial portion, said element being disposed within thetubular housing to electrically bridge the terminal contacts, one lowresistance end of the element directly contacting with one terminalcontact, and yieldable electrical conducting means between the other lowresistance end of the element and the other terminal contact formaintaining tension between it and the adjacent terminal contact and lowresistance end portion of the element and between the other lowresistance end portion of the element and the other terminal contact toassure a good electrical connection from one terminal contact to theother through the element.

3. A device for eliminating radio interference arising from highfrequency oscillations produced by the discharge of a spark plug,comprising a tubular housing of insulating material, a terminal contactat each end of the housing, a self-supporting electrical resistanceelement having its integra-l end portions of lower resistance value thanits medial portion, said element being disposed within the tubularhousing to electrically bridge the terminal contacts, yieldable meansfor maintaining a tension between the low resistance 'end portions ofthe element and the adjacent terminal contact to insure a goodelectrical connection between the element and the terminal contacts,means exteriorly of the housing facilitating the readily detachableconnection therewith of a conductor, and a combination mounting bracketand conductor electrically connected with the other terminal contact andadapted for connection with the electrode of a spark plug whereby theunit is supported therefrom.

4. A device for eliminating radio interference arising from highfrequency oscillations produced by the discharge of a spark plug,comprising a tubular protecting housing of insulating material, aterminal contact at one end of the housing, a terminal exteriorly of thehousing and in electrical connection with said terminal contact, aself-supporting electrical resistance element having integral endportions of lower resistance value than its medial portion within thehousing and adapted to have one end abutting said terminal Contact, acap member secured over the other end of the tubular housing, a terminalcontact carried by the cap member and adapted to be electricallyconnected with the other low resistance end of the resistance element,yieldable electrical conductor means engaging one end of the resistanceelement to maintain a tension between the element and the terminalcontacts, and a mounting bracket and terminal fixed to and supportedsolely from the cap member for mounting the dev1ce.

In testimony whereof I have hereunto affixed my signature.

WILLIAM F. STEENWEG.

